# Solving for base angles in a congruent triangle

1. Nov 27, 2013

### tomtomtom1

1. The problem statement, all variables and given/known data

Solving for base angles in a congruent triangle
One of the base angles in a congruent triangle is 3x+5
The other base angle is unknown
The remaining angle is x+16.

2. Relevant equations

See attached PDF

3. The attempt at a solution

Because two base angles in a congruent triangle are the same and I have been given one of them I did the following:-

3x+5 = 3x+5 (I then tried to solve for x but this cancels out to 0.)

I want to know why this is the case, i think it is because i have 2 unknown variables but only1 equation.

#### Attached Files:

• ###### triangle.pdf
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2. Nov 27, 2013

### Dick

As you said, the other base angle is 3x+5. You need to use something else. What's the sum of all of the angles of a triangle?

3. Nov 27, 2013

### tomtomtom1

The sum of the interior angles of a triangle is 180Degrees.

But i want to know if making 3x+5 equal to itself 3x+5 (3x+5 = 3x+5) am i trying to solve for 1 unknown with 1 equation or am i trying to solve 2 unknowns with 1 equations?

4. Nov 27, 2013

### SteamKing

Staff Emeritus
Setting 3x + 5 equal to itself implies 1 = 1. You need some other piece of information.

5. Nov 27, 2013

### Dick

As you said, the sum of your angles is 180 degrees. Write down an equation that expresses that.

6. Nov 27, 2013

### Curious3141

Also, why are you calling it a "congruent triangle"? Don't you mean "isoceles triangle"?

To expand on what others have said, what is the sum of the 3 angles in terms of x? Equate that expression to 180 degrees and solve.